Myelin is the multilayered membrane sheath surrounding axons. In the CNS, myelin is produced by the oligodendrocyte. One of the major components of myelin is myelin basic protein (MBP). The long range goal of this project is to elucidate the functional relationship between regulation of MBP gene expression and myelin morphogenesis. Previous studies indicate that regulation of MBP transcription, RNA translocation and protein localization are important in myelin morphogenesis. In this project, the cis/trans molecular mechanisms responsible for regulation at each of these levels will be analyzed in specifically informative genetic and cell culture systems. Genetic inactivation and reactivation of MBP gene transcription in the mouse will be studied by reversion analysis of mutations at the m1d locus. Cyclic AMP regulation of MBP transcription will be studied in a neurinoma cell line, using MBP-luciferase fusions and structural analysis of cryptic MBP RNA. Cellular and temporal regulation of MVP transcription during oligodendrocyte ontogeny will be studied using video intensified microscopy to monitor regulation of gene expression in living cells. Translocation of MBP RNA from the perikaryon to the periphery in oligodendrocytes will be studied by microinjection of synthetic MBP RNA. Plasma membrane localization of MVP will be studied by confocal immunofluorescent microscopy. The results will provide a detailed picture of the cis/trans molecular mechanisms involved in regulation of MBP gene expression. They will also set the stage for future experiments on the functional relationship between MBP gene expression and myelin morphogenesis, which will lead to a better understanding of demyelination diseases.